This invention relates generally to soldering or desoldering instruments and particularly relates to soldering tips therefor.
The soldering tip for a soldering instrument must conduct heat from the heater element of the instrument to a component to be soldered in an efficient manner. In addition, the solder tip should readily be wet by the solder compound. Furthermore, it needs to be easily cleaned and should not corrode at the usual soldering temperature due to the influence of flux and other corrosive chemicals.
To this end soldering tips are usually manufactured with a copper core which readily conducts heat. On the other hand, the copper easily corrodes and does not readily wet solder. Therefore, the copper core has conventionally been plated with a metal such as iron, steel or stainless steel. However, the plating process is fairly complicated and not easily controlled. For that reason, it has proven to be expensive. In addition, with this process it is first necessary to shape the copper core to the desired final form which may include a wedge-shaped tip. Further, for different operations solder tips of different sizes are necessary and this in turn means that a relatively large inventory of tips must be kept, each of which must be individually plated.
Furthermore, when a copper core is plated with iron or steel the wall thickness must be uniform and cannot be varied. This may be desirable in certain cases because the wall thickness determines the ease of heat transfer between the copper core and the outer shield: on the other hand, the outer shield provides mechanical rigidity and may have to be thicker at certain areas.
Another problem encountered in soldering instruments is the removal of the solder tip. It may either be necessary to remove a worn out tip and to replace it or alternatively, it may be desired to perform another soldering operation requiring a different type of solder tip.
Frequently, however, and particularly after extended use, the threads of the tip seize to the stainless steel sheath which conventionally surrounds the heater element. Therefore, considerable force may have to be used to remove the solder tip which in turn may damage the heater and hence necessitate replacement of the entire front end of the instrument.
For certain applications of temperature-controlled soldering instruments it may be necessary to operate the controlling electronics at relatively low voltage and high current. This may be necessary when the instrument is operated with dc line voltage. In this case, the silicon-controlled rectifier or power transistor of the instrument may generate considerable heat. Since these components are usually found in the handle of the instrument this may make it difficult to hold the instrument and may eventually damage the handle.
Therefore, a suitable heat sink is desirable to conduct the heat away from the handle, for example, along the cord of the instrument.
Finally, for the assembly of complicated components or for industrial applications it may be desirable to keep a record of the temperatures at which each component has been soldered. Therefore, a temperature sensor would be desirable which permits to display the temperature either by an oscilloscope or a strip chart recorder.
It is accordingly an object of the present invention to provide a solder tip for a soldering instrument which is laminated but which need not be plated.
A further object of the present invention is to provide a solder tip of the type discussed which after lamination with a suitable iron or steel can be further worked into a desired shape so that different forms of solder tips can be made from the same blanks.
Another object of the present invention is to provide a construction of the solder tip and associated sheath for holding the heater cartridge and heater which permits easy removal of the solder tip which may have seized without damage to the heater cartridge and the cartridge.
Yet another object of the present invention is to provide a sheath for the heater cartridge and heater which features rolled threads and a laminated construction to improve the heat transfer to the solder tip and facilitate its removal.
Still a further object of the present invention is to provide a temperature-controlled soldering instrument provided with two temperature sensors, one for controlling its temperature and the other for permitting a display of the actual temperature of the heater.
Still another object of the present invention is to provide an extra temperature sensor to permit digital temperature readout and sensitivity control of the readout in accordance with different solder tips.